162
FXUS66 KMFR 090345
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
845 PM PDT Mon Jul 8 2024

.DISCUSSION...The latest satellite shows more of the Shelly Fire
smoke moving north tonight. Overall, more areas in Northern
California and west of the Cascades in Southern Oregon will see
smoke and haze from the fires tonight and tomorrow and this has
been added to the forecast.

The forecast is still on track for west side locations to see more
highs in the triple digits with highs in the 90s east. There will
be a concern if the surrounding smoke becomes dense and impacts
afternoon warming. Either way, a concern of heat is present and a
Heat Advisory and Excessive Heat Warning remains tomorrow. Please
review the previous discussion for more information. -Hermansen

&&

.MARINE...Updated 800 PM Monday, July 8th, 2024...A thermal trough
will remain in place and dictate the sea state through the week.
This will mean a continuation of at least Small Craft Advisory
conditions through Wednesday night. Moderate to strong north winds
will continue to bring steep wind driven seas, especially south Cape
Blanco. The thermal through will strengthen late Wednesday night and
could bring gales south of Cape Blanco and beyond 5 nm from shore by
early Thursday morning and a Gale Watch has been issued.

Winds are expected to diminish some Friday into the weekend. Even
though winds could drop below gales, seas will likely remain very
steep and hazardous south of Cape Blanco, with conditions
hazardous to small craft. -Petrucelli

&&

.PREV DISCUSSION... /Issued 447 PM PDT Mon Jul 8 2024/

Updated Aviation Discussion.

SHORT TERM...A strong ridge of high pressure is centered over the
area today. The ridge axis will shift slightly eastward on
Tuesday as low pressure moves into the Gulf of Alaska. Very hot
temperatures and very dry conditions will persist across inland
areas through Tuesday. Then expect lingering heat into Wedensday.

Today and Tuesday, high temperatures will be around 20 degrees
above normal for inland areas with record setting highs likely
across inland areas. During this period, afternoon temperatures
are forecast to be around 105 to 115 for inland valleys west of
the Cascades and around 100 for valleys east of the Cascades.
Smoke from area wildfires may result in daytime temperatures
being 1-2 below guidance forecast but confidence remains high for
a continuing heatwave. Wildfire smoke is expected to also create
local air quality impacts in Jackson, Siskiyou, Klamath and Modoc
Counties, with strongest impacts downwind of the Salt Creek fire
(eastern Jackson County) and the Shelly fire (western Siskiyou
County). Higher level smoke aloft may impact a broader area of
southwest Oregon and northern California over the next couple
days. How much smoke we continue to see in the mid to late week,
will depend on wind flow as well as how active these fires are.

As a weak upper trough moves inland, well north of the area, the
high pressure ridge will weaken some on Wednesday This will
result in slightly less hot afternoon temperatures (but still
around 15 degrees above normal). However, heat impacts are likely
to continue through Wednesday for many areas including, eastern
Curry, Josephine, Jackson, Klamath, Lake, Siskiyou and Modoc
Counties.

Excessive Heat Warnings for areas west of the Cascades and Heat
Advisories for areas east of the Cascades are in effect through
Wednesday evening. Please see the NPWMFR for details.

Temperatures are expected to trend slightly less hot Thursday but
will remain well above normal. Friday into Saturday high
temperatures may trend slightly higher though as high pressure
strengthens. Additionally, during this period, high pressure will
be centered over the Four Corners region. This may allow monsoon
moisture to move up into the region. So, by Saturday afternoon
there is 5-10% chance of thunderstorms for areas east of the
Cascades, highest in Modoc and Lake Counties.

AVIATION...09/00Z TAFS...Along the coast and just offshore. VFR
conditions will prevail into this evening. Guidance shows marine
stratus forming later this evening with IFR ceilings and visibility
from Cape Blanco north and possibly lasting until mid morning
Tuesday. The timing of when conditions go from VFR to IFR could end
up developing on either side of the hour that`s in the North Bend
TAF. South of Cape Blanco, marine stratus should remain beyond 5 nm
from shore.

Inland VFR conditions will continue through the TAF period. The
exception will be in the vicinity of the Salt Creek and Shelly fires
where visibility could be reduced to less than 4 miles due to the
smoke. The afternoon valley flow is pushing the low level smoke out
of Medford, but the flow will weaken with smoke settling back into
the area tonight. -Petrucelli

FIRE WEATHER...

..Elevated to critical fire weather conditions possible all week...

Our trend of hot, breezy, low humidities, and occasional unstable
afternoon conditions will persist through this weekend. Our
afternoons are forecast to be above normal with deep mixing.
Fortunately the wind speeds are not too crazy this week, but they
certainly will be on the breezy side around 10-15 mph. Single digit
RH values are also forecast during the afternoon hours across the
eastside this week. These factors during this prolong drying stretch
will result in elevated to critical fire weather conditions nearly
every day this week. There are going to be a couple hours here and
there with criteria being met, but this afternoon and tomorrow
afternoon may fall just short of actually reaching criteria. While
no official warnings are out now, it will be very borderline today
and tomorrow afternoon. Conditions worsen as the week progresses,
and we will likely see Red Flag Warnings coming to fruition as early
as Thursday. That said, if conditions change now through Thursday,
we could see these conditions sooner as we are already close each
afternoon of reaching critical thresholds.

There is some relief from this heat by mid-week with a slight cool
down, but the reality is that temperatures are still going to be on
the warm side. Much of the area hasn`t received much rainfall, so
fuels are only going to worsen as this prolong drying stretch
continues with above normal temperatures. The heat is obviously of
importance for those outside fighting the fires.

-Guerrero

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 9 PM PDT Wednesday for ORZ023>026.

     Heat Advisory until 9 PM PDT Wednesday for ORZ029>031.

CA...Excessive Heat Warning until 9 PM PDT Wednesday for CAZ080>082.

     Heat Advisory until 9 PM PDT Wednesday for CAZ083>085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Thursday
     for PZZ356-376.

     Gale Watch from late Wednesday night through late Thursday night
     for PZZ356-376.

     Small Craft Advisory from midnight tonight to 5 AM PDT Thursday
     for PZZ370.

&&

$$